Limiting Mid Drive to Class 2
 

Hi all,

I'm thinking about converting a Trek Marlin 5 into an ebike with a 750w Bafang mid drive motor. I will use this bike mostly around town but I want to take it camping and ride some easy trails with it, also. I'm assuming I can, with programming, limit the top speed to 20mph. Would doing this then make this a Class 2 ebike and therefore legal on State and National Park trails?

TIA,
Eric

I have a 750w BBS02 even more severely limited with a 30 chainring and top speed of 18 mph or so on flat terrain. However, in socal, electric bikes are prohibited off road except where motor vehicles are allowed. It's a moot point however since there is policing in only a couple of easily avoided areas. Probably, you'll encounter the same situation; nobody is going to know or care that your bike is restricted.

Yes
a law is only as good as its implementation.
So is character and honor.
It's why we are having issues

For mountain biking you will want to reprogram the mid drive as the factory setting are appropriate for Chinese commuting, not mountain biking.
The first setting is about 40% power and will stuff you right in a tree. I have my first 7 levels programed as class 1 and the remaining two class 3. I am seldom in class three and never ran class 3 on mountain bike trails. Just remember, big dogs can run almost 30 mph and you will curse yourself for limiting top speed to 20 mph when trying to beat a storm.

I assume you're talking about reprogramming with software and a USB cable connecting my computer to the motor.

yes

@KPEN, Not trying to provoke , but I seldom see folks "trying to beat a storm", mostly just clowning.
That's the case for speed limiting cars as a safety measure, as well.
Yeah, it's gonna keep you from beating out the T-Rex in your rearview mirror, but the aggregate safety is increased.
Biking is about respecting the slower moving , cars vs bikes and pedestrians, and biasing towards the slower for a true net safety gain.
I am personally biased towards controlability and low speed assists in ebikes, but that starts debates that prevents compromises needed for integration.
Self control cannot be assumed in a lot of situations.

I take it that you have not toured with an e bike.

Given the vast numbers of ebike tourers, I can see that they should be the foundation of transportation strategy. :lol:
Realize in the 20's there was a strong movement for cars to be speed governed to 20 mph.

And where, exactly, did they get with that? All this is is just thinly veiled virtue signaling. There is no gun to any riders head forcing them to ride faster than 20mph because their motor is capable of more. If the o.p. really wanted to "be trail compliant" they would not be buying a 750W motor to try and restrict in a mid-drive configuration. All but impossible. The mid-drive has no control over the run out or the braking of a bike, all it can do is stop assisting once 20mph (or 28mph) is reached. Unless I way miss my guess, the Bafang is already set to do that out of the box.

It is only when you want to derestrict the motor (go faster illegally) that you have to get the computer and a serial cable out. Not so with a car. If they ever were to restrict cars to such and such a speed it would be easy to do, the Penske moving truck I rented once was speed limited to 75mph and by gum, so it was. Going down a mountainside with a two bedroom apartment worth of possessions and a four door sedan on a trailer and it did not go a single mph above the set limit no matter what. If y'all keep witching about it they may finally do the work necessary, and your e-bikes WILL be speed governed to 20mph period, end of story. When the pearl clutchers realize 20mph is actually pretty damn fast and very few people actually ride that fast all the time, you'll either ask for the limit to be even lower, or for e-bikes to be banned outright. I'm good with that. As long as there is an exception for Cargo and Utility bikes (and there will be) knock yourselves out. So, TL;DR ... when threads asking "how can I restrict my motor to be compliant" come up. The answer is: 'it already is restricted'. Unless you bought an illegal motor (and who would do that) it will already come Class 2. And if you know enough to ask the question, then you already know that.

It's not about virtue signaling. it's about good design.
Is it fun to go fast? duh.
Speed and safety are part of a complex algorithm, and there is a place on the curve that optimizes priorities.
Working together is one of those priorities.
Speed and safety tend be inversely related. Can you go, "what about being chased by tiger?" sure.
European standards tend to have speed max out at a reasonable 16 miles an hour. 20 kpm.
Can I pedal faster than that? Duh
We have a pretty poor governance of our transportation infrastructure. Unregulated speed is a part of that.
The answer is not "no governance", The answer is probably more along the lines of enforceable regulation.
And buy in by all the participants. It's a team sport.

Police where I am have all but stopped traffic enforcement.
Not surprisingly 10-15% drive like total jerks. Why not?
Injury accidents are reflecting that. Speed regulation is just part of the fix.

I'm pretty sure you have to de-restrict a bafang to go more than 20 unless the vendor has de-restricted it for you. But you usually have to ask.

I think the BBS01 & 2 are basically the same with different controllers, so if it were critical, the "02" controller could be replaced with an "01".

The Bafang 750 watt mid-drive I bought in August can do 28mph when riding singlespeed (44x17) using the throttle (simply can't pedal that fast in such gear). Haven't yet played with it enough with a derailer to find out if it increases with better gearing. Assuming it uses wheel RPM to calculate speed, it may not.

I was riding at 30 mph (50 kph) with 46:11 (AIR) before i basically restricted it to 20 or so with a 36:14 high gear. Probably it could have gone faster than 30, but that had the engine spinning fast enough for me.